It seemed that DNS lookups for Facebook, Twitter and YouTube were being censored as they returned from I-Root’s node in China, which is hosted by CNNIC.

There was no suggestion that Autonomica was complicit in any censorship, and chief executive Karl Erik Lindqvist has now confirmed as much.

“Netnod/Autonomica is 100% committed to serving the root zone DNS data as published by the IANA. We have made a clear and public declaration of this, and we guarantee that the responses sent out by any i.root-servers.net instance consist of the appropriate data in the IANA root zone,” he wrote.

While Lindqvist is not explicit, the suggestion seems to be that somebody on the Chinese internet not associated with I-Root has been messing with DNS queries as they pass across the network.

This is believed to be common practice in China, whose citizens are subject to strict censorship, but any such activity outside its borders obviously represents a threat to the internet’s reliability.

NeuStar has applied for a US patent on a stop-gap technology for authenticating DNS queries without the need for DNSSEC.

The application, published today, describes a system of securing the DNS connection between authoritative name servers and recursive servers belonging to ISPs.

It appears to cover the technology underlying Cache Defender, a service it started offering via its UltraDNS brand last July.

It was created to prevent the kind of man-in-the-middle attacks permitted by the 2008 Kaminsky exploit, which let attackers poison recursive caches, redirecting users to phoney web sites.

The DNSSEC standard calls for DNS traffic to be digitally signed and was designed to significantly mitigate this kind of attack, but it has yet to be widely deployed.

Some ccTLDs are already signed, but gTLD users will have to wait until at least this summer. The .org zone will be signed in June and ICANN will sign the root in July but .com will not be signed until next year.

While Kaminsky’s vulnerability has been broadly patched, brute-force attacks are still possible, according an ISP’s experience cited in the patent filing.

“The patch that experts previously believed would provide enough time to get DNSSEC deployed literally provided the industry just a few extra weeks,” it reads.